Simulations of the novel double-Penning trap for MLLTRAP: Trapping, cooling and mass measurements

Abstract

MLLTRAP is a double Penning trap mass spectrometer that was initially designed to be located at the Maier-Leibnitz-Laboratory (MLL) in Garching (Germany) for high precision mass measurements of exotic nuclei. A second double-trap assembly, dedicated this time to in-trap α decay spectroscopy, has been developed and is the object of this paper. This assembly can optionally replace the current mass-measurement trap electrode assembly during future spectroscopy campaigns at DESIR/SPIRAL2 in France. Though the previous assembly will be the instrument of choice for high-precision mass measurements, the new double-trap has been designed to be compatible with the ToF-ICR and PI-ICR mass measurement techniques in addition to its initial decay spectroscopy purpose, as it would be a significant operational advantage not to have to switch between assemblies on a regular basis. We have undergone a number of simulations to design this double trap system and estimate its future capabilities. These simulations concern the cooling of ions of interest in the first trap, mass measurements in the second trap and the application of the new Decay and Recoil Imaging (DARING) technique to measure lifetimes of first excited nuclear states populated by α decay. The latter will be described in details in a forthcoming publication and thus the present contribution should be considered as ”part one” of a two-part article on the design and simulation of the upcoming double-trap system for MLLTRAP. While the cooling and measurement techniques presented in this contribution have been extensively described and simulated in the past, this specific double-trap has a unique geometry, as the central electrode of the second trap has been replaced by a cubic arrangement of four Si-strip detectors. We study here the expected impact of this geometry on the mass measurement capabilities of the future trap.